Alphanumeric shellcode: Difference between revisions

Revision as of 14:32, 8 January 2006

Revision as of 14:31, 14 January 2006

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In general, in [[computing]], an '''alphanumeric code''' is a series of letters and numbers (hence the name) which are written in a form understandable and processable by a computer. One such alphanumeric code is [[ASCII]].

More specifically, in computer underground terminology alphanumeric code is [[machine code]] that is written so that it assembles into entirely readable [[ASCII]]-letters characters such as "a"-"z", "A"-"Z", "1"-"9", "#", "!", "@", and so on.

Writing alphanumeric code requires a good understanding of machine code encoding scheme for the specific architecture that the code is to executed on.

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==Example DOS-program==

%!!%BB-tz-!!-%cP\%!!%BB-=<Pu( ------Written by Kalle

The text above will, when interpretended by an [[x86]] [[Central processing unit|CPU]] using the [[DOS]] operating system [[self-modifying_codemodifying code|overwrite parts of itself]] with a code used to terminate the execution of the program, and return back to DOS. Just copy the text into an pure text editor (for example edit.exe in DOS or notepad in Windows), save the file and then rename it to "something.com". To execute the program, just type "something" in a DOS command shell.

[[Category:Security exploits]]